It can be appreciated that researchers have previously synthesized magnetite nanoparticles which can form ordered structures. For example, the dynamic tuning of structural color with a single material has been demonstrated by exerting an external magnetic field on a solution of superparamagnetic colloidal nanocrystal clusters (CNCs), see for example, Ge, J., Hu, Y. & Yin, Y., Highly tunable superparamagnetic colloidal photonic crystals, Angew. Chem. Int. Ed. 46, 7428-7431 (2007). These ordered structures diffract light such that various colors are produced, and wherein the wavelength of color depends on the spacing of the nanocrystals in the ordered structure. The spacing is tunable by altering properties of the nanoparticle, for example, the photonic band gap of CNC's can be altered to cover the whole visible spectrum with fast response time, as described in Ge, J. & Yin, Y., Magnetically tunable colloidal photonic structures in alkanol solutions, Adv. Mater. 20, 3485-3491 (2008). However, a cost-effective and scalable implementation of this feature in manufacturing would greatly simplify production of multicoloured goods such as electronics, displays, and vehicles.
In addition, previous work with nanocrystals has traditionally been limited to the use of polar solvents. Accordingly, it would also be greatly advantageous to be able to work with these materials in nonpolar solvents, which are compatible with manufacturing and processing techniques.
The present invention herein describes compositions comprising modified nanoparticles capable of being used in nonpolar solvents, modified nanoparticles in combination with solvent constituents, and methods of making and using these compositions.